Can you keep a standard rooster with a silkie?

Two weeks ago, my faithful little silkie roo lost his life protecting his girls from a hawk. When the spring comes, I want to replace him. Since the hawk seems to show up whenever I try to let the girls out now (which sucks, they were used to being out most of the day and now they are mostly stuck in their run), I was thinking it might be a good idea to go with a larger rooster. My only concern is that, out of my flock of 15, one of my girls is a silkie. Am I asking for trouble if I put her with a full-sized roo? I don't want her hurt, but I also don't want her eaten, and I figure she would be the most likely target. Thoughts? I've thought about even going with something like a Sumatra so there wouldn't be quite as big of a size difference.